In audio encoding and processing applications, prime importance is given to elimination of transfer non-linearities, noise injection and phase non-linearities.
In power amplifier applications, it is important to drive speakers and other output or transducer devices with relatively high power outputs. Use of devices which switch with extremely low rise and fall times serves to reduce output distortion as occurs in prior art devices. Non-linearities and noise in the input stage before comparator operation are nulled out by differential use of a pair of 180.degree. opposed sawtooths having identical frequency and zero phase shift between them. Differential input is from a common, constant current source. It is possible to eliminate distortions caused by encoding and amplification of the audio signal as it is introduced to the encoder/amplifier. Signal "ground", a common unbalanced mode noise source, is referenced to average duty cycle of output to achieve the low frequency response of a DC system with negligible offset or noise injection.